About 20 billion or more adipocytes are present in the human body, and when much more energy is supplied to the human body than the need for energy, energy is stored as triglyceride in adipocytes in the human body, and when energy is used up, the triglyceride is decomposed into free fatty acid and glucose and thus is used as an energy source. Obesity, which about 30 to 40% of modern people suffer from, occurs when excessive energy is accumulated due to the imbalance of the procedure, and is shown as a phenomenon in which the size of adipocytes is increased or the number thereof is increased.
The metabolic syndrome conceptualizes a clustering phenomenon of risk factors of various cardiovascular diseases and type 2 diabetes as one disease group. The metabolic syndrome is a concept which may comprehensively explain various metabolic abnormalities and clinical aspects, and refers to a syndrome in which risk factors such as obesity, diabetes, fatty liver, and hypertriglyceridemia are together increased. Accordingly, in the case of a metabolic syndrome, the risk of incidence of a cardiovascular disease or type 2 diabetes is increased.
Insulin resistance refers to a phenomenon in which, even though insulin is normally secreted in the body, a supply of glucose into cells, which is performed by insulin, does not work properly. Since glucose in the blood cannot enter cells, hyperglycemia is exhibited, and cells cannot perform normal functions thereof due to a shortage of glucose, and as a result, metabolic syndrome symptoms are manifested.
The diabetic symptom thus manifested is called type 2 diabetes (non-insulin-dependent diabetes mellitus: NIDDM) which is differentiated from type 1 diabetes (insulin-dependent diabetes mellitus) resulting from a shortage of insulin. For this reason, the most preferable method of treating type 2 diabetes is to induce insulin to be capable of performing normal functions thereof by alleviating insulin resistance. Nevertheless, a therapeutic agent of alleviating insulin resistance has hardly been developed up until now.
Most of the type 2 diabetes therapeutic agents currently used or developed aim to increase the amount of insulin secreted in order to supplement the functions of insulin lost by insulin resistance. However, when the amount of insulin secreted is increased from our bodies, not only obesity and inflammation are caused, but also various side effects such as an increase in cancer incidence rate are accompanied, so that unless the insulin resistance problem is alleviated, it is possible to expect that blood sugar is temporarily normalized, but the health is negatively influenced even more. For this reason, there is a more desperate social need for a type 2 diabetes therapeutic agent capable of normalizing blood sugar by alleviating insulin resistance.
Meanwhile, Patent Document 1 discloses that a pyranochromenyl phenol derivative is effective for preventing and treating a metabolic syndrome including hyperlipidemia, fatty liver, sugar metabolic abnormality, diabetes, and obesity, and have effects such as anti-inflammatory action.
Therefore, even though a method for efficiently and economically synthesizing the pyranochromenyl phenol derivative is very useful, a method for synthesizing the pyranochromenyl phenol derivative has been little known up until now, except for a method established based on a method for synthesizing (±)-glabridin (Non-Patent Document 1) developed by the present inventor.